DUNE FD Calibration workshop: How are

things going?

Sowjanya Gollapinni (UTK) Kendall Mahn (MSU)

DUNE Monthly Collaboration Call March 15, 2018

The workshop hasn’t ended yet :)

Calibration Strategy: Collaboration Process Timeline

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Workshop Goals/Format (https://indico.fnal.gov/event/16087/other-view?view=standard)

• Wednesday:

• Summary of current status

• Existing calibration sources

• Thursday:

• External Systems: Motivation, physics benefits etc.

• Discuss Key Questions/Concerns received so far

• https://docs.dunescience.org/cgi-bin/private/ShowDocument?docid=7449 

• Note down possible studies for TDR

• Friday:

• Dedicated session on DP considerations

• Summary, Agree on external systems and what goes into TP

• Workshop focus: External calibration systems & Physics benefits4

Attendance: 20 in-person

and 5-10 remote (productive discussions!)

Existing Sources Discussion• Better categorization of sources: Not all are calibration sources, some can only be

used to test models

• Emphasis that each source comes with unique challenge (e.g. Michels, Pi0s) — strong argument for redundancy

• Exchange rate of argon through the purification system can impact estimates timescales for measurements, need to take it into account

• Would be good to understand what are the measurements we need from ProtoDUNE and also how we can use it to test things for DUNE (e.g. DUNE electronics test)

• New estimates for cosmic muons from the MUSUN Cosmic Simulation shown

• Ar39: good source but (noise) threshold dependent; lifetime critical

• Need to understand radiological background and requirements for the detector. All consortia need to thinking about

• Current monitors as a source to diagnose resistor failures

Dual Phase Considerations• Dual Phase:

• Liquid and gas phase

• Ionization signals amplified and detected in the gaseous phase above liquid level

• 12m vertical drift in liquid argon

• Benefit of vertical drift: Cosmics provide enormous number of APA-CPA crossers

• Dedicated discussion on this later today

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Dual Phase Considerations• E-field distortions & impact on dQ/dx

• Space charge from Ar-39 for DP: not small; E-field1.0% (dQ/dx < 0.3%); Spatial 5 cm (dQ/dx 2 – 3%)

• plus E-field distortions from drift field deformations (cathode bowing, misalignment, APA flatness etc.)

• Argon flow pattern (steady state or turbulent) can significantly impact this. Even more complicated for DP: +ve ions may collect above the liquid and create surface interface issues.

• Does the gain vary with time? charge up from cosmic rays, how long does it take to go away?

• Interplay b/n Electron lifetime (3 ms requirement) and gain; Lower lifetime risky

• Requirements (and the ability to measure things) will change if we cannot achieve our nominal drift field

• Do impurities from gas enter the liquid phase? Will that an issue for lifetime? Temperature variations b/n gas and liquid phase can be an issue; flow pattern can also impact

Current Proposed Systems

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External Calibration Systems(currently considered)

• Laser (e.g. MicroBooNE, SBND) • Photo-electron (Laser) Calibration

System (e.g. T2K) • Radioactive source Calibration • Portable (external) Neutron source • Photon Detector Calibration system • Cosmic Ray Tagger (CRT) • Field response calibration

devices — not discussed

• New systems proposed/considered/discussed

• Radioactive sources also attached to cathode; injecting sources into argon

• T2K photo-calibration system — feasibility study planned

• Re-use of PDS system as light emitter? — bench tests and protoDUNE for feasibility

• Electron accelerator — exploratory studies needed

Discussion on Laser

• T2K-style photoelectron laser calibration system: similar to pulsing the cathode, a nice wake-up system to know things are alive

• Safety associated to SBND-style laser system discussed

• Laser head is plastic, but motor may include metal parts — need to assess

• Laser will sit 40 cm (in X) from APAs, low field; will NOT penetrate ground plane

• Post-workshop activity: Laser vs Cosmics statistics arguments require updating with new simulation-based cosmic numbers from T. Junk

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9 MeVGammas:

Neutrons:

Muon decay (Michels) endpoint ~50MeVElectrons:

6 MeV (captures)

K. Scholberg, E. Conley, J. Stock, J. Reichenbacher, R. Svboda, B. Littlejohn Low energy relevant energy scales

9 MeVGammas:

SN NC channel (10 MeV)

Neutrons:

Muon decay (Michels) endpoint ~50MeVElectrons:

6 MeV (captures)

SN CC channel

K. Scholberg, E. Conley, J. Stock, J. Reichenbacher, R. Svboda, B. Littlejohn Low energy relevant energy scales

9 MeVGammas:

Neutrons:

Muon decay (Michels) endpoint ~50MeVElectrons:

6 MeV total photon signal

νe

Neutron capture Low energy photons

Low energy EM response also relevant for LBL K. Scholberg, E. Conley, J. Stock, J. Reichenbacher, R. Svboda, B. Littlejohn

EM shower outliers

Source CalibrationK. Scholberg, E. Conley, J. Stock, J. Reichenbacher, R. Svboda, B. Littlejohn

• Neutron generator: - Outside field cage, illuminates entire detector with

capture events due to a anti-resonance - Characterizable capture spectrum (“bunch of standard

candles”)

• Radiological sources: • Deployment on cathode, outside field cage, or in fluid • Some natural (Ar39) some not (Thoron, Nickel) • Range in gamma energy, ability to stage deployments

• Sources serve as “standard candles”, direct test of efficiency of signal, background LE events with fixed position/energy/trigger

Discussion on Sources• External Neutron Source (Bob Svoboda)

• Better estimates on size of the system: 2 x 2 m cylindrical tank; 3 systems (fixed) can span the detector

• Human safety needs to be taken into account

• Will need a hole in insulation as in Feedthroughs, need to do shielding studies and understand needs

• Proposal to understand argon capture gammas at the LANSCE facility, LANL as a test bench

• Radioactive sources (Juergen/Jason)

• Studies from Juergen/Jason on charge-light correlation using simulation of Ni Calibration Source in the DUNE FD

• Developed MC cheating tools — huge effort ongoing

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Photon Calibration System (Zelimir Djurcic)

• UV-light based Photon Calibration System

• verifies gain, timing resolution; monitors stability and response over time

• light diffusers on cathode: safety discussed; some concern in how we route fibers safely

• Interesting idea (Stephen Pordes): can one use a flash lamp and generate electrons off the mirror? much simpler system

• Bench tests at ANL and an eventual test at ProtoDUNE as feasibility tests/studies

• Absolute Calibration (Nphotons to ADC Charge)

• Radioactive sources; cosmics

• New idea: Electron Accelerator?

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Electron Accelerator

(Zelimir Djurcic)

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Cosmic Ray Tagger (Josh Klein, Richard Diurba)

• Studies underway to understand the feasibility of the system

• Availability of space a consideration

• Agreement that a small portable system is more useful

• Provides simple/direct triggers

• In terms of motivation, growing agreement that it is best served as an independent handle for t0 and also as a reconstruction efficiency check

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DAQ Needs for Calibration (Matt Graham, Josh Klein, Kurt Biery)

• Better understanding of limitations from the DAQ side

• A total bandwidth of 30 PB/year for all 4 FD modules

• Other than random triggers, it is anticipated that the TPC threshold will be >10 MeV for normal running

• If event rate in detector is > 0.5 Hz, in existing paradigm event builder cannot keep up

• All data from front-end is passed to a temporary buffer, without zero suppression (~10 Tb/s/10 kt)

• If event rate in detector is > 1.6x106/year, you are dominant source of data for DUNE (unless events are zero-suppressed or geo-suppressed)

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DAQ Needs for Calibration• Some (very) rough initial estimates for annual data rates

currently in TP (see backup)

• Doesn’t include some systems (e.g. Ar39, PDS)

• Need to clarify estimates in the coming weeks

• Mitigation strategies on the 0.5 Hz event rate and transfer rates from underground location to surface discussed

• Didn’t loop in offline folks into the discussion yet, there maybe challenges on that front that needs to be considered

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TP & Post Workshop Goals• A document summarizing current status is in works

• The immediate goal after the workshop is to incorporate workshop discussions/responses/considerations into the summary document

• This document will form basis for the calibration section in Technical Proposal (2 to 3 page long?)

• Technical Proposal text due in April — we don’t have a lot of time

• Need to understand how much of calibration related discussions will be included in individual consortium chapters?

• Some coordination required here so details are up to date with discussion in Calibration TF meetings

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Summary• Workshop has been fun so far:

• Additional ideas and their motivation raised

• Many key questions answered or studies identified

• Please join us for the final discussion at the workshop!